Manufacture of optical fibre cables with simultaneous laying

Abstract

A cable comprising a central armour, a dielectric helically grooved core and an optical fibre housed in each one of the plurality of the grooves is produced by extrusion of the profiled core on the armour, pulling vertically the core through an annular laying unit comprising a plurality of take off reels supplying optical fibre guiding each of said fibre within one of the grooves by mechanical and pneumatic means and taping fibre filled core.

What we claim is: 
     
       1. Process for the manufacture of cable elements comprising a central armour, a helically grooved extruded core on said armour, optical fibres within said grooves and a protective tape, characterized by the following steps: horizontal pulling of the armour of high mechanical strength,   extruding a dielectric plastic core in accordance with the grooved profile of the element,   cooling the core,   drying and preheating the core,   turning the core along a vertical axis through a horizontal annular carrier supporting a set of optical fibre supply reels,   simultaneous guiding each optical fibres within a groove of the core under the combined action of gravity and of forces exerted by a gas under pressure,   taping the core,   pulling the core along the vertical axis,   taking up the element on a reel of horizontal axis.   
     
     
       2. Process for the manufacture of cable elements according to claim 1, wherein the means for the supply of optical fibre, the extrusion, the taping, the pulling and the take-up of the element are rotating, and the armour core not rotating. 
     
     
       3. Process for the manufacture of cable elements of the type under consideration according to claim 1, wherein the carrier supporting the optical fibre reels turns about a vertical axis. 
     
     
       4. Process for the manufacture of cable elements as recited in claim 1, wherein the guiding of the fibres is effected by a frustoconical member having in its upper part of maximum diameter a series of vertical nozzles communicating with grooves of omega-shaped profile whose dimensions decrease with their distance from the upper part and which are machined in its internal face, and a series of horizontal nozzles on the lower part, also communicating with the slots, said fibres are through the grooves of said member by the air expelled by said vertical nozzle and pass into the grooves of the cable core, said member carries a centering pin cooperating with a positioning slot in the core. 
     
     
       5. Process for the manufacture of cable elements as recited in claim 1, wherein the guiding of the fibres is effected by a set of two coaxial crowns disposed one below the other and coaxial with the cable, the upper crown having a series of apertures through which the optical fibres are engaged and having a diameter which is large in relation to that of the core, the lower crown being of similar diameter as the core of the cable and having apertures in its internal face carrying one end of a plurality of capillaries, the other end of which is introduced into one core groove said capillaries being passed through by the fibres.